1. Field of the Invention
The present invention relates generally to germicidal disinfecting compositions. More particularly, the present invention relates to a novel concept for germicidal disinfecting compositions that are effective in killing both vegetative microorganisms and microbiological spores in a single composition.
2. Related Art
Microbiological spores are among the most resilient forms of dormant life known to man. Although formed by many different types of microbiological organisms, the most commonly studied spores are from various Bacillus or Clostridium species. In particular, Bacillus spores are amazingly resistant to common sterilizing techniques. For example, most vegetative bacteria die quickly when subjected to temperatures in excess of 80° C., but bacterial spores often survive boiling water at 100° C. for two hours or more. Spores have survived for 20 years in 70% alcohol solutions and can survive one million rems of radiation. Drying has little effect on spores, as demonstrated by spores surviving in the intestines of Egyptian mummies for thousands of years. [I. Edward Alcamo, (2001) Fundamentals of Microbiology, 6th ed., Jones and Bartlett Publishers, Sudbury, Mass.].
Spores are formed by bacteria when nutritional resources are low. The resulting spores have certain compartments and layers. The central core, referred to as the protoplast, contains soluble enzymes and genetic material. The spore protoplast is surrounded by a spore membrane that functions as a boundary for the spore protoplast, as a regulator of cell permeability, and as a structural matrix for certain enzymes. A germ cell wall is immediately external to the spore membrane, composed primarily of peptidoglycan. The next layer is the spore cortex, also composed of modified peptidoglycan. Many of the properties of the protective cortex layer are attributed to this component such as the regulation of spore size and permeability. The spore coat represents 30–60% of the dry spore weight, contains approximately 80% of the total spore proteins, and occupies about 50% of the spore volume. The spore coat is extremely resistant to a variety of drastic chemical treatments, suggesting that the coat plays an important role in spore resistance. The exposporium, or outermost spore layer varies in structure and composition from species to species of bacteria.
Spores remain dormant until germination is triggered by external stimuli. Many types of spores are activated by heat or by certain chemical substances such as calcium dipicolinate and amino acids, most particularly L-alanine. Activation is the initial event in germination, an irreversible process that converts dormant spores into metabolically active ones within a short period of time. Initiation of germination is followed rapidly by a number of degradative changes in the spore. The protective coating around the spore begins to open and becomes more permeable to water, causing the germinated spores to swell. Reducing agents that reduce disulfide cystine linkages in proteins and enzymes that attack peptidoglycan linkages also weaken the spore coat and increase permeability of the spore. As germination proceeds, the spores shed their outer layers, allowing the young, vegetative cells to emerge, elongate, and divide. Development of a vegetative cell from a germinated spore is called outgrowth.
A safe and effective topical skin care formulation capable of killing microbiological spores and preventing their subsequent development into infectious, vegetative cells is desired and needed. Furthermore, it is also desired that the formulation be gentle to skin, provide a cosmetically pleasing feel and assist in gently moisturizing the skin, such that the user will gain benefit from both the microbiocidal activity and improved skin health through repetitive application.